Examination will be continued of the kinetics and mechanisms of reactions of hemerythrin, the oxygen-carrying protein derived from the coelomic fluid and retractor muscle of Themiste zostericola and other sipunculan worms. The properties of the half-reduced and half-oxidized forms (semi-mets) of hemerythrin, first characterized in our previous work, will be further investigated. This will involve EPR collaborative studies and kinetics of reactions with a variety of redox reagents. It is anticipated that conventional, flow and temperature-jump techniques will all be employed. Flash photolysis studies of oxy- and met-hemerythrin derivatives will be initiated. It is hoped that the results will a) allow an assessment of the effect of the oligomeric character of the protein on its reactivity, b) help characterize the binuclear iron sites and intramolecular electron transfer involving them, c) give data for oxygenation of deoxyhemerythrin and d) show up photochemical effects. Comparisons will be sought with other iron-containing proteins.